The present technique relates generally to the measurement of the overall motion undergone by an organ. More specifically, the present technique relates to measuring the motion of one or more internal organs via one or more external sensors and/or via data acquired from a medical imaging system to determine the overall motion of at least one of the internal organs.
In the medical field, it is often desirable to generate images of the internal organs or structure of a patient for diagnosis or examination. For example, magnetic resonance imaging and computed tomography are two well known examples of imaging modalities used to generate images of the internal organs or structures of a patient. The reconstructed images, however, may be flawed or contain artifacts due to the motion of internal organs, such as the heart, lungs, diaphragm, stomach, and so forth. In particular, if the imaged region has undergone motion during the imaging process, various motion related artifacts or discontinuities may be present in the reconstructed image.
To reduce or eliminate the effects of internal motion, gating techniques may be employed which utilize information about organ motion to minimize the effect of the organ motion during imaging. Gating techniques that use organ motion information to time the acquisition of imaging data are known as prospective gating techniques. Conversely, those that use organ motion information to selectively process or reconstruct previously acquired imaging data are known as retrospective gating techniques.
The organ motion information used for gating typically represents the contractions, convulsions, or extensions of the organ of interest. However, due to the spatial relationship of the various internal organs, many of which undergo some form of motion, gating techniques that address only a portion of the overall motion of an organ may produce images that still possess motion artifacts. For example, the rhythmic contractions of the heart, which may be determined using various techniques such as electrocardiography (ECG) or mechanical cardiography, may be used in gating the acquisition and/or reconstruction of cardiac image data. Measuring the contractions of the heart, however, only partially describes the overall motion of the heart. The motion of other organs, such as the respiratory motion of the lungs or diaphragm, may also be moving the heart relative to the viewer or imaging scanner. Consequently, knowing the cardiac motion attributable to the heart alone, such as the phase of cardiac motion, may not be sufficient to fully describe the overall motion of the heart relative to the imaging scanner, which may reduce the benefits obtainable by gating techniques. It may, therefore, be desirable to more fully characterize the motion undergone by an internal organ during imaging for purposes of gating or motion correction.